Radiotelegraphy



A. L; ANDER-SION RADIOTELEGRAPHY Filed Dec. 25 1919 INVENTOR' @.ndersod Patented May 8, 1923.

HEUTE@- S'IAFEES ADRIEN L. ANDERSON, OF PALO ALTO, CALIFOENIA,"ASSIGNOR TO AUGUSTUS TAYLOR, OF SAN FRANCISCO, CALIFORNIA,

f' Maase? retreat ferien.'-

RADIOTELEGRAPHY.

Application led December 23, 1919. Serial No. 346,913;

To all whom t may concern.'

Be it known that I, ADRIEN L..ANDERsoN, a citizen of the United States, and a resident of Palo Alto, Santa Clara County, State of California, ,have invented certain new and useful Improvements in tadiote-A legraphy, of which the following is a speciiication.

The invention relates to radio telegraphy and particularly to radio telegraphy transmission systems.

An object of the invention is to provide a single Wave radio signaling system.

The invention possesses other advantageous features, some of which, with the foregoing, will be set forthl at length in the following description where I shall outline in full those embodiments of the invention which I have selected for illustration in the drawings accompanying and forming part of the present specification. In said drawings, I- have shown several lforms of my invention, but it is to lbe understood that I do not limit myself to such forms, since the invention, as expressed in the claims, may be embodied in other forms.-

Referring to said drawings:

Figure 1 is a diagrammatic representationl of a radio telegraphy transmission system embodying my invention.

Figure 2 is a diagrammatic represental tion of a modiiedform of the system.

Figure 3 is a diagrammatic representation of a modified form of system particularly suitable `for high 'powered stations.

Figure 4 is a further modified form of the invention. n

The system includes a suitable source of oscillations, such as the arc 3 which operates in a hydrogen atmosphere and is subjectedto a strong, transverse magnetic field, produced by the combined magnet and choke coil 4:. The arc is grounded on one side, preferably, the negative, and is connected on the other side to the antenna 5, through the variable inductanceor antenna loading coil 6. Direct current is supplied to the arc by ,the generatorV 7. Shunted across the arc is a second loscillatory vcircuit contain'ingy an inductance 8 yand a capacitance 9, 'and this circuit is preferablyk tuned to the same frequency as the antenna circuit. i

lrareasiaethe impedance of. theshunt circuit, the arc maybe ymade to oscillate upon the antenna circuit vto the practical neglectof the `shunt circuit and conversely, by making the impedance of Atheantenna circuit greater than that vof tjhe shunt circuit, the arc will prefer to oscillate on the shunt circuit to the practical neglect of the antenna circuit. Signaling may therefore be readily accomplished by varying ,the relative impedance of the two circuits'and. when the arc is oscillating on the shunt circuit, no oscillations are radiated from lthe antenna circuit.

The variation of theimpedance g, of the antenna circuit is accomplished by opening and closing a resistance circuit which 1s coupled to the inductance coil .6.. This circuit is provided with a signaling key 12,

which the circuit is coupled to the coil 6. Similarly, the impedance of the shunt circuit` is varied by opening and, closing the key 15 in the circuit containing the in lductance-coil 16, coupled to the inductance a resistance 13 and a coil 14 by means of i prefer the antenna circuit and it oscillates thereon. l

The inclination of the arc'to oscillate on the antenna circuit is augmented bytheincrease in reactance of the shunt circuit due to the detuning lof this circuit bythe closingof the key 15. The closing ofthe key 15 causes the arc tol oscillate onthe antenna circuit by addingl resistance` to the shunt circuit, and, its oscillations have thel rfrequency ofthe antenna circuit, since the frequency of oscillations, such as those pro- ,y

duced byan arc converter, i's'thelnatural frequency of the circuit connected to the arc. Closing of the key 15 decreases the in.- du'ctance of the coil 8 by mutual inductance and transformer action between it and the coil 16. Thus the natural frequency ofthe shunt circuit becomes greaten than that of the antenna circuit when the key 15is closed., @hemmt of increase@ ,frequency depending upon the inductance of the coil 16 and the coupling between it and the coil 8. Therefore, the shunt circuit no longer has Zero reactance to the impressed oscillations since a series circuit containing an inductance and a capacitance and connected to a source of oscillations, will have zero reactance to said oscillations only when its natural frequency is equal to that of the inipressed oscillations, and that its reactance becomes greater as its natural frequency is made greater or less than the frequency of the impressed oscillations; in other words, the closing of the key 15 not only has the e'ect of adding resistance to the shunt circuit but it also adds reactance to this circuit by detuning it.

lt should be noted that when the key 15 is closed current flows through it for only an instant, since its closing adds impedance to the shunt circuit, with the result that the current from the are is transferred to the antenna circuit; thus. when the contacts 15 open, they yopen with practically no load upon them. This feature makes it possible to handle a large amount of power with few relay keys.

TWhile l have shown two resistance circuits, one coupled to the antenna loading coil 6 and the other coupled to the shunt circuit inductance 8, it is to be understood, that in some instances, the circuit coupled to the loading coil 6 may he dispensed with, and the system operated by varying the impedance of the shunt circuit only, but in such a system it is often found in practice that there remains in the antenna circuit a residual current when the arc is oscillating on the shunt circuit. and since this residual current is practically eliminated by the use of the two resistance circuit systems, I prefer to use the latter.

The keys 13 and 15 are preferably connected together` either mechanically.l as by a rod 18 of insulating material to which a signaling key 19 is secured, or electricallyy as shown in Figure 2 wherein the keys 12 and 15 are operated by solenoids 21 and 22 in the circuit of the signaling key 23. Depression of the signaling key` opens the key 12 and closes the key 15, causing the arc to oscillate on the antenna circuit and releasing the signaling key opens the key 15 and closes the key 12, causing the arc to oscillate on the shunt circuit.

One of the advantages of coupling the resistor circuit to the inductance of the oscil "latory circuit rather than shunting it around few turns of the inductance is that this arrangement permits the adjusting of the ytn urrent and voltage to be handled by the key to values that permit most efficient operation Loffthefkey, itbeing known that there is a 'certain voltage and a certain current at which a pair of contacts will work most efficiently,

that is, at which minimum sparking occurs.

Another advantage is that the key does not have to be insulated from earth for a very high voltage.

Another advantage obtained by coupling the resistor circuit to the oscillatory circuit is that one pair of contacts may be made to handle the power of a very large transmitter by the arrangement shown in Figure 3, where a number of loops or coils 241-25 connected respectively in parallel and coupled to the inductances 6 and 8. rl`his arrangement produces a very large current in the key circuit, lout this is not detrimental,

.since the current flows only at the instant of closing of the contacts. T he size of the loops is so made that the voltage produced in them is the maximum that the key contacts will stand without detrimental sparking.

The arrangement shown in Figure 3 shows a further simplification of the system in wiich only one resistor is used which functions alternately in each of the two resistor circuits.

One side of the circuit of the coils 241 connected to one side of the circuit of the coils 25 by a conductor 26 which is connected tothe switch arm 27 of the double contact switch 28 through a resistor 29. Movement of the switch arm to one side closes the circuit of the coils 24 through the resistor and movement of the switch arm to the other side closes the circuit of the coils 25 through the resistor.-

ln the construction shown in Figure l, when the key 'l2 is closed and the key 15 is onen. and the arc is oscillating on the shunt circuit and signals are not being radiated from the antenna. there will still be a small current flowingin the antenna, due to the in-phase voltage impressed upon it by the arc. The frequency of this residual current is that of the shunt circuit and not the natural frequency of the detuned antenna circuit and the value of the current will depend upon the impedance that has been inserted in the antenna circuit. Usually, its value is only a small percentage of the total antenna current and its presence is not detrimental. but if desired it may he eliminated or an proximately eliminated. A means for ac, comnlishing this result is shown in Figure 2, wherein a resistance 21 is arranged in the antenna circuit. This resistance is shunted by a substantially resistanceless circuit 32 in which is inserted a key 33 which is connected to the signaling key 23 in such manner that depression of` the signaling key closes the shunt circuit 32, thereby cutting the resistance outl of theantenna circuit. The key is timed so that its opening lags the closingl of the kev 12.

ln high powered stations. wherev on e key is insuicient to handle the load, a plurality of loops inductively connected to each inclued tance may be employed, and each loop circuit may be provided With a key and means provided for operating the keys in the loops coupled to one inductance simultaneously or substantially so.

In Figure 4 I have shown a plurality of loops 84 coupled to the inductance 8, each loop being provided with a key! 35. The keys may be operated mechanically or electrically as hereinbefore set forth. A similar plurality of loops are coupled to the inductance 6 and the keys in said loops are operated by the same means employed for operating the keys 35, but in the opposite direction.

I claim:

l. In a radio telegraphy transmission .system, a source of oscillations, a radiating circuit containing inductance connected to said source, a circuit containing resistance inductively coupled to said inductance, a non-radiating oscillatory' circuit containing inductance shunted around said source, a circuit containing resistance inductively coupled to said last named inductance and means for opening and closing the resistance circuits.

2. In a radio telegraphy transmission system, a source of oscillations, a radiating circuit connected to said source, a non-radiating oscillatory circuit shunted around said source, a circuit inductively coupled to the radiating circuit, a circuit inductively coupled to the non-radiating circuit, a resistor common to both of said inductively coupled circuits and a key for alternately closing one coupled circuit through the resistance and opening the other coupledcircuit.

3. In a radio telegraphy transmission system, a source of oscillations, a radiating circuit, a non-radiating circuit shunted around said source, a circuit inductively coupled to the radiating circuit, a second circuit inductivelyI coupled to the non-radiating circuit, and means for closing one of the inductively coupled circuits while opening thek other, in such manner that the closed circuit includes a substantial amount of resistance.

4:. In a radio telegraphy transmission system, a source of oscillations, a radiating circuit, including an inductance coil, connected to said source, an oscillatory circuit, including an inductance coil, shunted around said source, a circuit including a plurality'of loops in parallel coupled to the radiating circuit inductance, a circuit containing a plurality of loops in parallel coupled to the shunt circuit inductance, a key arranged to ,Y

open one of said latter circuits and 'close the other and a resistance in the closed circuit.

5. In a radio transmitting system having a source of oscillations, a radiating circuit,

so',I

and a circuit shunted around the source,

means for varying the constants of both circuits so as to alter their energy loss characteristics, comprising circuits inductively coupled to the first mentioned circuits,vand

circuits.

means for opening and closing said coupled 6. In a radio transmitting systernhaving an arc for producing oscillations, a radiating circuit, and an absorption circuit,means loss characteristics of the coupled circuits whereby the characteristic of oneis oppo-` site to that of the other. ,v v

7. In a radio transmitting system having an arc Yfor producing oscillations, a radiating circuit, and an absorption circuit, means for causing the arc to oscillate substantially! entirely on one or the #other of these circuits, comprising a circuit inductivelycoupled to the radiating circuit, a second circuit inductively coupled to the absorption circuit, a resistor, and means for connecting the resistor in either of the two coupled circuits, so as to complete that circuit.

In testimony whereof, I have hereuntoset y California, this 15th my hand at Palo Alto, day of December, 1919.

ADRIEN L '.l ANDERSON.- 

